The present invention relates generally to semiconductor packaging and assembly and, more particularly, to a method and system for achieving planar alignment of a substrate during solder ball mounting.
Improvements in semiconductor packaging and assembly are rapidly being made by semiconductor manufacturers with the overall goal of increasing productivity while reducing material waste. These improvements typically result in semiconductor products that can be produced more cheaply and in greater quantity.
The actual process of packaging and assembling semiconductor products usually involves a series of steps. One such step, such as for packaging flip chips, involves positioning a substrate-type material on a specially designed movable support for receiving a solder, such as solder balls, from a solder depositing member. In operation, once the substrate has been positioned, the solder is then carefully deposited thereon. Conventionally, the substrate is sometimes misaligned or tilted with respect to the solder member, during the deposition of solder balls, which leads to the inaccurate placement of solder, the waste thereof, and decreased yields.
Accordingly, there exists a need for a semiconductor packaging and assembling method and system that stabilizes, with great precision, a substrate material positioned on a moveable fixture with respect to the solder depositing member during the application of the solder balls. This system would advantageously allow for positioning of the substrate, making it less sensitive to tilting and warping as the solder is deposited thereon. Advantageously the system would also maintain the planar alignment of the substrate, with the solder mounted thereon, as it is moved from one stage in packaging and assembly process to another.
The present invention achieves technical advantages as a system and method capable of allowing solder to be mounted on a substrate with greater precision even if the substrate is slightly misaligned, warped, or tilted. Thus, rather than relying on the planarity of the substrate standing alone as it sits on a retractable support, the invention provides a pivotable substrate support which allows for mounting of the soldering compound to occur by firmly dictating the angle of planarity of the substrate before and after the solder is deposited thereon.
In one embodiment the present invention is a system used to precisely deposit a compound on a substrate, such as solder balls applied to a flip chip. The system generally includes a receiving member having a pivotable portion which comprises a rotating vacuum coupling. The receiving member is adapted to hold a generally planar substrate. The system also includes a horizontal member, comprising a ball mount, for depositing solder balls on the substrate. To fix the planarity of the substrate as the solder ball are deposited thereon, the invention includes a contact member located between the receiving member and the horizontal member to secure the substrate during attachment of the solder balls. The contact member, comprising an aligner plate, has stoppers protruding therefrom, such that the stoppers, together with the rotating action of the vacuum coupling, combine to firmly fix the substrate in a substantially planar position before and after the solder balls are deposited thereon.
In another embodiment, the invention is a method of setting the planarity of a substrate with respect to the solder ball apparatus before and after a solder is deposited thereon. The method generally begins with the act of positioning a substrate on a receiving member which has a rotatable portion, and is then followed by contacting and securing the substrate with a fixed contact member, comprising an aligner plate having protruding stoppers, that establishes the planar alignment of the substrate before and after the solder is deposited thereon.